Have you ever experienced one or more "Eureka" moment(s) in your language studies?

Often, when studying a language (and also in other learning journeys), some people experience a "Halleluja!"/"Eureka!"/"Bingo!"/"Abracadabra!" moment, where something important suddenly makes sense after a long period of confusing and perplexing them.

Did you bang your head on a (metaphorical!) brick wall for years then suddenly notice the wall fall away and crumble beneath your feet?

What do you think was the catalyst? What caused the ground-breaking, earth-shattering sudden breakthrough for you?